A method of modeling a time-varying drive propulsion system

Abstract

The application discloses a modeling method of a time-varying transmission propulsion system. The method comprises the following steps: modeling excitation sources of the propulsion system respectively to obtain corresponding excitation target models; wherein the excitation sources comprise propeller time-varying uncertainty excitation, bearing oil film, gear box excitation and universal coupling, and the excitation target models comprise a propeller excitation model, an oil film load time-varying model, a gear box excitation model and a universal coupling model; modeling a propulsion shafting to obtain a propulsion shafting model; coupling and loading the propeller excitation model, the oil film load time-varying model, the gear box excitation model and the universal coupling model to the propulsion shafting model to obtain a time-varying transmission propulsion system model with multiple excitation sources. The method solves the problem of single excitation source in the modeling method and cannot be applied to accurate simulation under sudden strong vibration conditions, realizes the establishment of a time-varying transmission propulsion system model with multiple excitation sources, is suitable for different operation conditions and guarantees normal operation of a ship.

Description

Technical Field

[0001] This invention belongs to the field of ship design technology, and more specifically, relates to a modeling method for a time-varying transmission propulsion system. Background Technology

[0002] The propulsion system in a ship plays a crucial role; however, its operating environment is relatively harsh, and it is constantly subjected to complex loads, inevitably leading to various problems. Among these, the ship's propulsion shaft system plays a vital role in the generation of hull structural vibration and radiated noise.

[0003] Marine propulsion systems mainly consist of propellers, gearboxes, universal couplings, and main engines. To calculate propeller-induced pulsating pressure, three methods are commonly used: theoretical calculation, empirical formula estimation, and experimental methods. Empirical formulas mainly include the Holden method, the Takahashi method, and the Fujino method, while experimental methods primarily include model tests and full-scale ship testing.

[0004] However, these methods all have some limitations in practical applications. Traditional methods require tedious numerical analysis. Furthermore, in actual operation, the excitation generated by these components is often time-varying, and the excitation force is not constant, which leads to uncertainties in the vibration response of the entire system. Under this condition, if the shafting system operates under uncertain vibration for a long time or under sudden strong vibration, it may lead to deviations in bearing load capacity, loosening of shafting accessories, and even threaten the normal and safe operation of the ship. Summary of the Invention

[0005] In view of the shortcomings of related technologies, the purpose of this invention is to provide a modeling method for time-varying transmission propulsion systems. This method aims to solve the problems of existing modeling methods having a single excitation source, which cannot be applied to the accurate simulation of sudden strong vibration conditions, resulting in deviations in bearing load capacity, loosening of shaft accessories, and even threatening the normal and safe operation of ships.

[0006] To achieve the above objectives, the present invention provides a modeling method for a time-varying transmission propulsion system, comprising:

[0007] The excitation sources of the propulsion system are modeled to obtain corresponding excitation target models; wherein, the excitation sources include: propeller time-varying uncertainty excitation, bearing oil film, gearbox excitation and universal coupling, and the excitation target models include: propeller excitation model, oil film load time-varying model, gearbox excitation model and universal coupling model;

[0008] The propulsion shaft system is modeled to obtain the propulsion shaft system model;

[0009] The propeller excitation model, the oil film load time-varying model, the gearbox excitation model, and the universal joint model are coupled and loaded onto the propulsion shaft system model to obtain a time-varying transmission propulsion system model with multi-source excitation.

[0010] Optionally, the time-varying uncertainty excitation of the propeller in the propulsion system is modeled to obtain the propeller excitation model, including:

[0011] A sample function for generating a convex model is used, and the response boundary of the propeller excitation force is calculated based on the sample function.

[0012] The convex model process is sampled to obtain load sample curves over time.

[0013] The propeller excitation model is obtained based on the load sample curve and the Monte Carlo simulation method.

[0014] Optionally, the bearing oil film of the propulsion system is modeled to obtain a time-varying model of the oil film load, including:

[0015] Based on the hydrodynamic lubrication theory, a two-dimensional Reynolds equation is established for the oil film of sliding bearings, and its boundary conditions are determined.

[0016] The two-dimensional Reynolds equations were solved using the finite difference method, and the pressure distribution at the oil film nodes was solved using the point-by-point relaxation iterative method.

[0017] The load and tilt angle parameters at the bearing obtained through calibration calculations;

[0018] The journal balance position corresponding to the centering attitude is obtained based on the load and the tilt angle parameters, and the oil film stiffness is calculated.

[0019] The time-varying model of the oil film load is obtained based on the oil film node pressure distribution and the oil film stiffness.

[0020] Optionally, the gearbox excitation of the propulsion system is modeled to obtain a gearbox excitation model, including:

[0021] A virtual prototype model of the gearbox was created on the MSC.ADAMS simulation platform;

[0022] Based on elasticity theory, a collision definition is made for each gear contact pair in the virtual prototype model to obtain gear meshing impact excitation.

[0023] The gear meshing impact excitation was simulated and calculated to obtain the gearbox excitation model.

[0024] Optionally, the universal joint of the propulsion system is modeled to obtain a universal joint model, including:

[0025] The kinematic relationship between the driving shaft fork, the cross shaft and the driven shaft fork in the universal coupling is analyzed by using the coordinate transformation method. The relationship between the fixed coordinate system and the rotating moving coordinate system is obtained through Euler transformation.

[0026] Universal coupling models corresponding to different rotational speeds, torques, and angular differences are established on the fixed coordinate system and the rotating coordinate system.

[0027] Optionally, the step of modeling the propulsion shaft system to obtain a propulsion shaft system model includes:

[0028] The displacements of the substructures of the propulsion shaft system are described using the spectral geometric series method;

[0029] A spring system is used to simulate the elastic boundary and structural coupling conditions of the propulsion shaft system;

[0030] Energy functional variational analysis is performed on the displacement of the substructure, the elastic boundary, and the structural coupling conditions to establish a propulsion shaft system model with vibration characteristics.

[0031] Optionally, after coupling and loading the propeller excitation model, the oil film load time-varying model, the gearbox excitation model, and the universal joint model to the propulsion shaft system model, the method further includes:

[0032] The propeller, shaft system, and thrust bearing in the propulsion shaft system model are simplified by using a lumped mass, rod, and spring-damping-mass system simulation.

[0033] The thrust bearing base in the propulsion shaft system model was simplified using Timoshenko beam simulation.

[0034] The time-varying transmission propulsion system model with multi-source excitation is obtained based on the simplified propulsion shaft system model.

[0035] In summary, compared with the prior art, the above-described technical solutions conceived by this invention can achieve the following beneficial effects:

[0036] 1. This invention provides a modeling method for time-varying transmission propulsion systems, applicable to the main excitation source model and parameter time-varying excitation coupled shaft system model under different ship operating conditions. It can be used to guide the dynamic structural design of ship transmission propulsion systems and has important practical value and guiding significance. It also provides a technical foundation for future research on coupled structure vibration and vibration reduction and noise reduction analysis.

[0037] 2. This invention provides a modeling method for a time-varying transmission propulsion system, realizing the establishment of a multi-source excitation time-varying transmission propulsion system model. It can be applied to the main excitation source model and parameter time-varying excitation coupled shaft system model under different ship operating conditions, making the established model more consistent with engineering reality. Furthermore, the vibration response in actual application is more consistent with the expected simulation results, thereby ensuring the good condition of the hull and the normal operation of the ship.

[0038] 3. This invention provides a modeling method for time-varying transmission propulsion systems, capable of analyzing the vibration response of shaft systems under uncertain lateral and longitudinal excitations, and establishing a model suitable for uncertain vibration analysis of shaft systems. Comparative analysis of the response boundaries under various operating conditions is performed to gain a deeper understanding of the vibration response. Attached Figure Description

[0039] Figure 1 This is a flowchart illustrating a modeling method for a time-varying transmission propulsion system provided in an embodiment of the present invention. Detailed Implementation

[0040] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0041] The following description, in conjunction with a preferred embodiment, illustrates the content involved in the above embodiments.

[0042] like Figure 1 As shown, a modeling method for a time-varying transmission propulsion system includes:

[0043] S1. Model the excitation sources of the propulsion system respectively to obtain the corresponding excitation target models; wherein, the excitation sources include: propeller time-varying uncertainty excitation, bearing oil film, gearbox excitation and universal coupling, and the excitation target models include: propeller excitation model, oil film load time-varying model, gearbox excitation model and universal coupling model;

[0044] S2. Model the propulsion shaft system to obtain the propulsion shaft system model;

[0045] S3. Couple the propeller excitation model, oil film load time-varying model, gearbox excitation model and universal coupling model to the propulsion shaft system model to obtain a time-varying transmission propulsion system model with multi-source excitation.

[0046] The model of a time-varying propulsion system is a complex system model that requires consideration of multiple factors to predict its performance and behavior. Key components of the system include the actuator, the transmission system, and the propulsion system. The actuator can be a propeller, gearbox, or other form of energy source, and the transmission system can transfer the excitation energy to the propulsion system via gears or a hydraulic system.

[0047] The method provided in this embodiment decomposes the main excitation sources of typical ships, including propellers, gearboxes, hydraulic couplings, and universal joints, based on the excitation loads experienced by typical ships under different operating conditions. Considering the time-varying characteristics of excitation forces, excitation load spectrum modeling methods are established for propellers, main engines and gearboxes, and universal joints, respectively.

[0048] Factors to consider in modeling include: the exciter's output capability and stability, including parameters such as power, torque, and speed; the transmission efficiency and power loss of the transmission system, including friction, inertia, and other factors; the thrust generation capability and stability of the propulsion system, including blade angle, gas flow rate, and other parameters; and the influence of the operating environment, including temperature, humidity, altitude, and other factors. By considering these factors and using experimental data and theoretical analysis, an accurate time-varying transmission propulsion system model can be established for applications such as performance prediction, fault diagnosis, and optimization design.

[0049] Optionally, the time-varying uncertainty excitation of the propeller in the propulsion system is modeled to obtain the propeller excitation model, including:

[0050] A sample function for generating a convex model is used, and the response boundary of the propeller excitation force is calculated based on the sample function.

[0051] The convex model process is sampled to obtain load sample curves over time.

[0052] The propeller excitation model is obtained based on the load sample curve and the Monte Carlo simulation method.

[0053] Time-varying uncertainty excitations refer to uncertainties arising from the environment or internal factors that affect a system, with the characteristics and intensity of these excitations changing over time. This uncertainty is typically caused by environmental diversity and system complexity, such as weather changes, traffic flow fluctuations, and machine wear. The impact of time-varying uncertainty excitations on a system is severe, as it can lead to drastic changes in system performance, such as instability, vibration, or noise problems. Therefore, accurate modeling and analysis of time-varying uncertainty excitations are crucial for ensuring the normal operation of a system.

[0054] Monte Carlo simulation is a stochastic simulation method widely used in risk analysis, financial modeling, and physical simulation. Its basic idea is to estimate the probability distribution or statistical characteristics of a system or process by repeatedly conducting random trials using random sampling. Specifically, Monte Carlo simulation simulates the randomness of input parameters, using numerical models or algorithms to simulate the behavior of a system or process, thus solving many problems that traditional methods cannot address.

[0055] Optionally, the bearing oil film of the propulsion system is modeled to obtain a time-varying model of the oil film load, including:

[0056] Based on the hydrodynamic lubrication theory, a two-dimensional Reynolds equation is established for the oil film of sliding bearings, and its boundary conditions are determined.

[0057] The two-dimensional Reynolds equations were solved using the finite difference method, and the pressure distribution at the oil film nodes was solved using the point-by-point relaxation iterative method.

[0058] The load and tilt angle parameters at the bearing obtained through calibration calculations;

[0059] The journal balance position corresponding to the centering attitude is obtained based on the load and the tilt angle parameters, and the oil film stiffness is calculated.

[0060] The time-varying model of the oil film load is obtained based on the oil film node pressure distribution and the oil film stiffness.

[0061] The Reynolds equation is a fundamental conservation equation in fluid mechanics, playing a crucial role in all aspects of fluid motion. In engineering, the Reynolds equation is widely used in aircraft design, ship hydrodynamics, combustion flow fields, seismology, aerodynamics, and the design and analysis of various systems for oil and gas transportation and airflow control.

[0062] Optionally, the gearbox excitation of the propulsion system is modeled to obtain a gearbox excitation model, including:

[0063] A virtual prototype model of the gearbox was created on the MSC.ADAMS simulation platform;

[0064] Based on elasticity theory, a collision definition is made for each gear contact pair in the virtual prototype model to obtain gear meshing impact excitation.

[0065] The gear meshing impact excitation was simulated and calculated to obtain the gearbox excitation model.

[0066] The propulsion system gearbox used in this embodiment has multiple input shafts and an additional PTO / PTI motor. To address the challenges of a more complex transmission structure and more input shafts, the MSC.ADAMS simulation platform and elastic collision theory were employed for research. By establishing a virtual prototype model and defining the collision for each pair of gear contact pairs, the gear meshing impact excitation generated in the transmission system under rated operating conditions can be simulated and calculated. Finally, a pair was selected for verification to confirm the accuracy of the simulation calculations.

[0067] For the dynamic models of various components in a gearbox (such as gears, bearings, and drive shafts), dynamic theory is adopted, based on the energy method and the infinitesimal element method, considering the influence of various nonlinear factors on the dynamic system, and a corresponding dynamic model is established. By dimensionless processing of variables such as displacement, velocity, and acceleration in the dynamic equations, the relationships between various parameters are summarized, and the influence of each parameter on the characteristics of the established dynamic model is further analyzed.

[0068] Gear meshing impact excitation refers to the impact force generated during gear meshing. Due to factors such as the discreteness of gear tooth profiles, gear axis deviation, and uneven gear mass distribution during meshing, irregular impact forces are generated during gear movement. These impact forces produce vibration and noise during gear transmission and can also damage the gears themselves. Solutions to the gear meshing impact excitation problem include improving gear materials and manufacturing processes to increase gear strength, hardness, and wear resistance. Simultaneously, careful consideration must be given to parameters such as meshing angle, number of teeth, module, and tooth surface shape when designing gear systems to reduce the generation of gear meshing impact excitation.

[0069] Optionally, the universal joint of the propulsion system is modeled to obtain a universal joint model, including:

[0070] The kinematic relationship between the driving shaft fork, the cross shaft and the driven shaft fork in the universal coupling is analyzed by using the coordinate transformation method. The relationship between the fixed coordinate system and the rotating moving coordinate system is obtained through Euler transformation.

[0071] Universal coupling models corresponding to different rotational speeds, torques, and angular differences are established on the fixed coordinate system and the rotating coordinate system.

[0072] A universal joint is a mechanical component used to transmit torque and rotational angle changes between shafts. It typically consists of two universal joints and a central tube connecting them. It can rotate freely in both angular and axial directions, thereby connecting two shafts and transmitting torque and rotation between them.

[0073] The universal coupling of the propulsion system used in this embodiment is based on the multi-rigid-body dynamics theory. The characteristics of the secondary excitation force under different speed, torque and angle difference conditions are analyzed, and the corresponding kinematic model is established.

[0074] Optionally, the step of modeling the propulsion shaft system to obtain a propulsion shaft system model includes:

[0075] The displacements of the substructures of the propulsion shaft system are described using the spectral geometric series method;

[0076] A spring system is used to simulate the elastic boundary and structural coupling conditions of the propulsion shaft system;

[0077] Energy functional variational analysis is performed on the displacement of the substructure, the elastic boundary, and the structural coupling conditions to establish a propulsion shaft system model with vibration characteristics.

[0078] The spectral geometry method is a mathematical approach used to study problems based on geometric structures. Based on spectral theory, it represents the object of study (such as a manifold or operator) in spectral form, that is, by performing a Fourier transform or discrete Fourier transform on it, obtaining its Fourier coefficients at specific frequencies. By appropriately processing and combining these Fourier coefficients, information about the geometric structure of the object of study can be obtained.

[0079] The method in this embodiment also includes a time-varying uncertainty vibration analysis method for transmission and propulsion systems. This method solves for the upper and lower response boundaries of the system or structure based on the characteristic parameters of the time-varying uncertainty of the input excitation. Taking a multi-degree-of-freedom coupled system as an example, it performs time-varying uncertainty vibration calculations. Considering the vibration response of the transmission and propulsion system under different operating conditions of time-varying excitation uncertainty, it analyzes the shaft uncertainty vibration problem under different rotational speeds and bearing stiffness variations.

[0080] Optionally, after coupling and loading the propeller excitation model, the oil film load time-varying model, the gearbox excitation model, and the universal joint model to the propulsion shaft system model, the method further includes:

[0081] The propeller, shaft system, and thrust bearing in the propulsion shaft system model are simplified by using a lumped mass, rod, and spring-damping-mass system simulation.

[0082] The thrust bearing base in the propulsion shaft system model was simplified using Timoshenko beam simulation;

[0083] The time-varying transmission propulsion system model with multi-source excitation is obtained based on the simplified propulsion shaft system model.

[0084] The technical solution of this invention decomposes typical ship excitation sources, including propellers, bearing oil films, gearboxes, and universal couplings, and constructs excitation models for each, resulting in a multi-source excitation model. This multi-source excitation model is then coupled and loaded onto the propulsion shaft system model, thus obtaining a time-varying transmission propulsion system model with multi-source excitation. This solves the technical problem in existing modeling methods where the excitation source is singular, making it unsuitable for accurate simulation under sudden strong vibration conditions. This leads to deviations in bearing load capacity, loosening of shaft system accessories, and even threats to the normal and safe operation of the ship. The invention achieves the establishment of a multi-source excitation time-varying transmission propulsion system model, applicable to main excitation source models and parameter time-varying excitation coupled shaft system models under different ship operating conditions. This makes the established model more consistent with engineering reality, and the vibration response in actual applications better matches the expected simulation results, thereby ensuring good hull condition and normal ship operation.

[0085] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A modeling method for a time-varying transmission propulsion system, characterized in that, include: The excitation sources of the propulsion system are modeled to obtain corresponding excitation target models; wherein, the excitation sources include: propeller time-varying uncertainty excitation, bearing oil film excitation, gearbox excitation and universal coupling excitation, and the excitation target models include: propeller excitation model, oil film load time-varying model, gearbox excitation model and universal coupling model; The propulsion shaft system is modeled to obtain the propulsion shaft system model; The propeller excitation model, the oil film load time-varying model, the gearbox excitation model, and the universal joint model are coupled and loaded onto the propulsion shaft system model to obtain a time-varying transmission propulsion system model with multi-source excitation.

2. The modeling method for a time-varying transmission propulsion system as described in claim 1, characterized in that, A model is constructed to address the time-varying uncertainty excitation of the propeller in the propulsion system, resulting in a propeller excitation model, including: A sample function for generating a convex model is used, and the response boundary of the propeller excitation force is calculated based on the sample function. The convex model process is sampled to obtain load sample curves over time. The propeller excitation model is obtained based on the load sample curve and the Monte Carlo simulation method.

3. The modeling method for a time-varying transmission propulsion system as described in claim 1, characterized in that, A time-varying model of the bearing oil film in the propulsion system is obtained by modeling the oil film load, including: Based on the hydrodynamic lubrication theory, a two-dimensional Reynolds equation is established for the oil film of sliding bearings, and its boundary conditions are determined. The two-dimensional Reynolds equations were solved using the finite difference method, and the pressure distribution at the oil film nodes was solved using the point-by-point relaxation iterative method. The load and tilt angle parameters at the bearing obtained through calibration calculations; The journal balance position corresponding to the centering attitude is obtained based on the load and the tilt angle parameter, and the oil film stiffness is calculated. The time-varying model of the oil film load is obtained based on the oil film node pressure distribution and the oil film stiffness.

4. The modeling method for a time-varying transmission propulsion system as described in claim 1, characterized in that, The gearbox excitation of the propulsion system is modeled to obtain the gearbox excitation model, which includes: A virtual prototype model of the gearbox was created on the MSC.ADAMS simulation platform; Based on elasticity theory, a collision definition is made for each gear contact pair in the virtual prototype model to obtain gear meshing impact excitation. The gear meshing impact excitation was simulated and calculated to obtain the gearbox excitation model.

5. The modeling method for a time-varying transmission propulsion system as described in claim 1, characterized in that, The universal joint of the propulsion system is modeled to obtain the universal joint model, including: The kinematic relationship between the driving shaft fork, the cross shaft and the driven shaft fork in the universal coupling is analyzed by using the coordinate transformation method. The relationship between the fixed coordinate system and the rotating moving coordinate system is obtained through Euler transformation. Universal coupling models corresponding to different rotational speeds, torques, and angular differences are established on the fixed coordinate system and the rotating coordinate system.

6. The modeling method for a time-varying transmission propulsion system as described in claim 1, characterized in that, The process of modeling the propulsion shaft system to obtain a propulsion shaft system model includes: The displacements of the substructures of the propulsion shaft system are described using the spectral geometric series method; A spring system is used to simulate the elastic boundary and structural coupling conditions of the propulsion shaft system; Energy functional variational analysis is performed on the displacement of the substructure, the elastic boundary, and the structural coupling conditions to establish a propulsion shaft system model with vibration characteristics.

7. The modeling method for a time-varying transmission propulsion system as described in claim 1, characterized in that, After coupling and loading the propeller excitation model, the oil film load time-varying model, the gearbox excitation model, and the universal joint model onto the propulsion shaft system model, the method further includes: The propeller, shaft system, and thrust bearing in the propulsion shaft system model are simplified by using a lumped mass, rod, and spring-damping-mass system simulation. The thrust bearing base in the propulsion shaft system model was simplified using Timoshenko beam simulation. The time-varying transmission propulsion system model with multi-source excitation is obtained based on the simplified propulsion shaft system model.

Images